Voltage stability proximity indicator in frequency domain based on the modified Jacobian matrix model

In this paper, based on the modified Jacobian matrix model, a power system voltage stability proximity indicator in the frequency domain is presented. This indicator can be used to measure the proximity to voltage instability which is caused by either Hopf bifurcation or saddle node bifurcation. It is different from the voltage stability indices presented previously, which only take into account the occurrence of saddle node bifurcation. The results of two power systems show that the proposed indicator can approach nearly `linearly´ to zero in a wide interval around the system critical point